1. Field of the Invention
The present invention relates to an apparatus and method for overcoming angular deviations in a workpiece, and, more particularly to an apparatus and method for permitting crowning and localized adjustment of bending surfaces of press equipment in order to compensate for sagging and irregularities in the shape of the surfaces.
2. General Background and State of the Art
Traditional press equipment, such as a press brake has a stationary lower bed with an elongate surface for supporting a first press tool and a moveable upper bed with an elongate surface for supporting a second press tool. Generally, the first press tool associated with the stationary bed is a forming die held in a die holder and the second press tool is a punch. In operation, the moveable bed or ram is moved downwardly toward the forming die to bend, shape or otherwise form a workpiece placed between the forming die and the punch. Alternatively, the lower bed may be configured to move upwardly towards a stationary upper bed.
The compressive forces applied to the workpiece by the co-operating punch and die are quite high, generally exceeding several tons. As the upper and lower beds that support the punch and die are typically supported at their longitudinal ends, sagging of the beds tends to occur. In addition, irregularities in the bed surfaces or the press tools can result in non-constant bending of the workpiece over the length of the workpiece.
Various arrangements are used to overcome sagging. In a technique referred to as crowning adjustment, the overall curvature of the surface of at least one of the beds is adjusted to compensate for sagging. A convex curvature is termed positive crown, while a concave curvature is a negative crown. One such crowning arrangement is shown in U.S. Pat. No. 4,898,015 to Houston. This arrangement includes two transverse wedges which extend over the length of the beds of the press brake.
Although such arrangements are used to adjust the overall curvature of the beds, there is still a need to compensate for localized irregularities due to such factors as wear and machining tolerances. This is generally achieved in a technique commonly called localized adjusting which involves raising or lowering the bed surface at particular locations to compensate for local irregularities.
U.S. Pat. No. 5,009,098 to Van Merksteijn is an example of an arrangement that provides for both crowning and localized adjusting. Van Merksteijn includes curve-forming members slidable over each other in the lengthwise direction for crowning adjustment, and in the transverse direction for localized adjustment. However, crowning and localized adjustment by distortion of the curve-forming member both longitudinally and transversely can cause the arrangement to be susceptible to failure due to compound stresses. In addition, because the curve-forming members are unitary pieces, transverse movement to effect localized adjustment at one position of the bed surfaces tends to inadvertently affect localized adjustment at immediately adjacent positions. The result is that localized adjustment can become a time consuming iterative process which involves making an adjustment at the desired position, measuring the shape of the bed surface adjacent the desired position to determine how it has been affected, making adjustments to remove inadvertently introduced changes, and then going back to determine any introduced changes at the desired position.
Therefore, it would be desirable to have an alternative apparatus and method that provides for crowning and localized adjustment of the bed of press equipment. It would be further desirable to have an apparatus and method that provides an improved technique for localized adjustment.
In accordance with one aspect of the present invention there is provided an apparatus for adjusting the shape of an elongate surface having inner and outer surfaces comprising a plurality of interconnected shaping members spaced apart from each other and extending longitudinally along the inner surface, the shaping members adapted to permit adjustment of an overall curved shape of the elongated outer surface by co-ordinated longitudinal movement, relative to the elongated surface, of groups of the shaping members with respect to each other and adapted to permit adjustment of one or more localized portions of the overall shape of the elongated outer surface by independent longitudinal movement of one or more individual shaping members relative to the elongated outer surface.
The shape forming system may be positioned in a longitudinal groove of a die rail positioned on the lower bed surface of a press brake.
In accordance with another aspect of the invention there is provided a press comprising:
a frame;
an upper bending member and a lower bending member supported by the frame, the upper and lower bending members being moveable relative to each other to apply force to a workpiece placed between the upper and lower bending members; and
a shape forming system associated with at least one of the upper and lower bending members for adjusting the shape of the bending member, the shape forming system comprising a plurality of interconnected shaping members spaced apart from each other and extending along the bending member to permit adjustment of the overall curved shape of the bending member by co-ordinated slidable movement of the shaping members over each other in a longitudinal direction relative to the bending member and to permit localized adjustment of one or more portions of the overall shape of the bending member by independent longitudinal movement of one or more of the shaping members relative to the bending member.
In another aspect of the present invention there is also provided an apparatus for adjusting the shape of an elongate bed member in press equipment, the bed member being formed with a channel to define an elongate inner surface opposite an elongate outer surface comprising:
a plurality of shaping members insertable within the channel to extend longitudinally of and engage the inner surface, each shaping member being formed from a wedge member and an associated link member movable with respect to the wedge member, each link member being connected to adjacent link members;
whereby co-ordinated slidable longitudinal movement of the link members over the wedge members permits adjustment of the overall curved shape of the outer surface and independent slidable longitudinal movement of individual wedge members permits adjustment of one or more localized portions of the overall shape of the outer surface.
Each wedge member may be formed with an inclined surface at angle xcex1 and the wedge members may be arranged in a pattern along the elongated surface such that angle xcex1 decreases from the middle of the elongated surface to distal ends of the elongated surface.
Each link member may include a base member and a contact member mounted together to permit pivoting movement of the contact member with respect to the base member to maintain contact with the longitudinal surface. Each base member and contact member may be formed with one of an opposed mutually engaging convex and concave surface to permit pivoting of the contact member. The base members may be interconnected by rigid links having two ends. Each rigid link may be pivotally mounted to each base member.
In yet another aspect, there is provided a method for adjusting the shape of a elongate surface having an outer surface and an inner surface comprising the steps of:
providing a plurality of interconnected shaping members spaced apart from each other and extending longitudinally along the inner surface;
moving the shaping members as a group in a longitudinal direction relative to the outer surface to adjust the overall curved shape of the elongated outer surface; and
moving one or more individual shaping member independently in a longitudinal direction relative to the outer surface to adjust one or more localized portions of the overall shape of the elongated outer surface.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.